The present invention relates to a disposable puncture aid, and in particular, a disposable puncture aid whose reuse is prevented by a blocking element.
Samples of body fluids, in particular, blood, are taken with the aim of carrying out a subsequent analysis, in order to permit diagnosis of diseases or to monitor the metabolic status of a patient. Such samples are taken by diabetics, in particular, for determining blood sugar concentration. In order to collect only small quantities of blood for diagnostic purposes, sterile, sharp lancets are normally used which, for example, are briefly inserted by hospital staff or by the patients themselves into the finger pad or into other parts of the body. In the area of home monitoring in particular, where persons without specialized medical training carry out simple analyses of blood themselves, lancets and associated devices (blood sampling devices, blood lancet devices or, as they are referred to in the following description, “puncture aids”) are sold which allow samples of blood to be taken with the least possible discomfort and in a reproducible manner.
Disposable puncture aids that include a mechanism to prevent multiple use are known in the prior art. Allowing multiple use of a puncture aid introduces a risk of the user being contaminated or infected by blood residue present on the lancet of the puncture aid.
U.S. Pat. Nos. 6,764,496 and 6,514,270 each relate to a disposable lancet device for single use, with a lancet which is arranged in the interior of a housing and which is movable between a tensioned position and a puncture position. A restrictor assembly is designed such that it engages the lancet and ensures that, after movement into the puncture position, the lancet cannot be moved back again to the tensioned position.
U.S. Pat. No. 6,719,771 relates to a blood sampling device that includes a sleeve with a spring-loaded lancet which can be released from a tensioned, rearward position by means of a trigger mechanism, in order to allow its tip to project instantaneously from the forward end of the sleeve. The lancet has a deflectable or releasable attachment which can be engaged with the sleeve and which holds the lancet counter to the pressure of the spring, the attachment extending rearward from the lancet and engaging behind a projection which is provided on an inner structure of the sleeve. The lancet is released by the trigger, which is formed integrally with the sleeve and is pressed transversely with respect to the sleeve, which unlocks the attachment. Moreover, when activated, the trigger can enter into a snap-fit engagement with the sleeve in order to retain the latter in its activated position.
The subject matter of EP 1 371 329 A1 (and corresponding U.S. patent application Ser. No. 10/437,717) is a puncture aid comprising a housing which has an opening and in which a lancet holder with a lancet is displaceably mounted. The lancet holder is connected to a spring element and includes at least one bearing element. At least one support surface is arranged in the housing in such a way that the bearing element rests on the support surface in a first position of the lancet holder. The puncture aid also comprises a trigger unit by means of which the lancet holder is transferred to a second position, a trigger button of the trigger unit executing a linear movement, and the linear movement being converted into a relative movement of the bearing element and the support surface with respect to one another. In the second position of the lancet holder, the bearing element falls from the support surface, and the spring element, tensioned prior to the falling movement, at least partially relaxes and moves the lancet holder relative to the housing, so that the tip of the lancet emerges from the opening of the housing.
This puncture aid according to EP 1 371 329 A1 has the disadvantage that, by using a suitable tool in the form of an elongate element that can be inserted through the opening into the housing, the bearing element can be returned to the support surface by means of a linear movement and a subsequent rotation movement. Depending on the design of the sterile protector, the latter itself can even serve as a tool for renewed tensioning of the puncture aid. Undesired reuse of the puncture aid is therefore possible. EP 1371 329 A1 proposes a system of protection against reuse in which, after the puncture process, the bearing element is pressed upward by a spring element against the support surface. However, even with such a system of protection against reuse, renewed tensioning of the puncture aid by using a tool cannot be prevented.